1. Field of the Invention
The present invention relates generally to a liquid crystal display device, and more particularly to a liquid crystal display device which includes a pixel electrode on an array substrate, includes a counter-electrode on a counter-substrate, and generates a transverse electric field between the pixel electrode and the counter-electrode.
2. Description of the Related Art
In recent years, flat-panel display devices have vigorously been developed, and liquid crystal display devices attract particular attention by virtue of their advantages of light weight, small thickness and low power consumption. In particular, in an active matrix liquid crystal display device in which a switching element is provided in each of pixels, attention has been paid to the structure which makes use of a transverse electric field (including a fringe electric field), such as an IPS (In-Plane Switching) mode or an FFS (Fringe Field Switching) mode (see, for instance, Jpn. Pat. Appln. KOKAI Publication No. 2005-3802).
The liquid crystal display device of the IPS mode or FFS mode includes a pixel electrode and a counter-electrode, which are formed on an array substrate, and liquid crystal molecules are switched by a transverse electric field that is substantially parallel to the major surface of the array substrate. In addition, polarizer plates, which are disposed such that their axes of polarization intersect at right angles, are disposed on the outer surfaces of the array substrate and the counter-substrate. By this disposition of the polarizer plates, for instance, at a time of non-application of a voltage, a black screen is displayed, and with the application of a voltage corresponding to a video signal to the pixel electrode, the light transmittance (modulation ratio) gradually increases and a white screen is displayed. In this liquid crystal display device, the liquid crystal molecules rotate in a plane that is substantially parallel to the major surface of the substrate. Thus, since the polarization state is not greatly affected by the direction of incidence of transmissive light, there is the feature that the viewing angle dependency is low and a wide viewing angle characteristic is obtained.
A transverse-electric-field-mode liquid crystal display device having a pixel electrode and a counter-electrode on one of the substrates cannot be fabricated by using a conventional process of a vertical-electric-filed mode liquid crystal display device, such as a TN (Twisted Nematic) mode liquid crystal display device, which has a pixel electrode and a counter-electrode on different substrates. Thus, different manufacturing lines are needed, or the manufacturing line needs to be reassembled. This may cause an increase in manufacturing cost.
Furthermore, in the transverse-electric-field-mode liquid crystal display device, it is difficult to form an electric field, which is parallel to the major surface of the substrate, over the pixel electrode. Thus, compared to the vertical-electric-filed mode liquid crystal display device, the transmittance is lower.